We undertook a re-analysis of the Canadian data from the thirteen-country INTERPHONE case-control study (2001-2004), which evaluated the association between mobile phone use and risk of brain, acoustic neuroma, and parotid gland tumors. The main publication of the multinational INTERPHONE study concluded that “biases and errors prevent a causal interpretation”. We applied a probabilistic multiple-bias model to address possible biases simultaneously, using validation data from billing records and non-participant questionnaires as information on recall error and selective participation. Our modelling sought to adjust for these sources of uncertainty and to facilitate interpretation. For glioma, the odds ratio comparing highest quartile of use (over 558 lifetime hours) to non-regular users was 2.0 (95% confidence interval: 1.2, 3.4). The odds ratio was 2.2 (95% confidence interval: 1.3, 4.1) when adjusted for selection and recall biases. There was little evidence of an increase in the risk of meningioma, acoustic neuroma, or parotid gland tumors in relation to mobile phone use. Adjustments for selection and recall biases did not materially affect interpretation in our Canadian results.

It is noteworthy that statistically significant increased risk was found already at 558+ hours of cumulative use corresponding to 9 min per day during 10 years. This amount is much lower than now used for wireless phones. Total Interphone showed for cumulative call time, 1640 hours or more, odds ratio 1.40 (95% confidence interval 1.03–1.89) for glioma. This corresponds to less than half an hour per day (27 min) during 10 years.

We have read this article in the New York Times with interest. However, there are several mistakes, and even wrong statements, on the health hazards from exposure to radiofrequency electromagnetic fields (RF-EMF) from cell phones in the article. In the following we want to correct some of the false statements.

The brain is the primary target organ for exposure to RF-EMF during the use of the handheld wireless phone. This has given concern of an increased risk for brain tumours. The carcinogenic effect of RF-EMF on humans was evaluated at a meeting during 24 – 31 May 2011 at the International Agency for Research on Cancer (IARC) at WHO in Lyon, France. One of us (LH) was part of the expert group. The Working Group categorised RF-EMF from mobile phones, and from other devices that emit similar non-ionising electromagnetic fields in the frequency range 30 kHz–300 GHz, as a Group 2B, i.e. a possible, human carcinogen (http://monographs.iarc.fr/ENG/Monographs/vol102/mono102.pdf).

Since then more studies have been published that strengthen the association between use of wireless phones (mobile and cordless phones) and increased risk for brain tumours. We have performed long-term research in this area and in the following we give a short up-dated summary of our findings based on research since the 1990’s. In our publications relevant information can be found also on other studies, as well as discussions of the current scientific evidence.

Glioma:

Glioma is a malignant brain tumour (“brain cancer”), and the most common type is glioblastoma multiforme with a poor prognosis. We have published a statistically significant increased risk for glioma among users of both mobile and cordless phones. The risk increased with latency (time from first use of the phone) and cumulative number of hours for use. Highest risk was found in the area of the brain with highest exposure to RF-EMF. All these results are of biological relevance; that is what would be expected for a causal association. The full paper can be read here: http://www.pathophysiologyjournal.com/article/S0928-4680(14)00064-9/pdf

Meningioma:

Meningioma is mostly a benign brain tumour and accounts for about 30 % of all intracranial tumours. The incidence is approximately 2-times higher in women than in men. No conclusive evidence of an association between use of mobile and cordless phones and meningioma was found in our study. However, taking the long latency periods that have been reported for the increased meningioma risk associated with exposure to ionizing radiation it is still too early to make a definitive risk assessment. Results for even longer latency periods of wireless phone use than in our study are desirable, see more details here: http://www.spandidos-publications.com/or/33/6/3093

Acoustic neuroma:

Acoustic neuroma or Vestibular Schwannoma is a rare benign tumour in the eighth cranial nerve that leads from the inner ear to the brain. It grows slowly and does not undergo malignant transformation, but may give compression of vital brain stem centres. Tinnitus and hearing problems are usual first symptoms of acoustic neuroma. We published a clear, statistically significant, association between use of mobile and cordless phones and acoustic neuroma. The risk increased with time since first use. For use of both mobile and cordless phones the risk was highest in the longest latency group. Tumour volume increased per 100 hours of cumulative use and year of latency for wireless phones indicating tumour progression from RF-EMF. The whole study can be read here: http://www.spandidos-publications.com/ijo/43/4/1036

Due to the well-known under-reporting of brain tumours to the Swedish Cancer Registry we studied brain tumour rates using the Swedish National Inpatient Register and the Causes of Death Register. In summary we found a statistically significant increasing rate of not specified brain tumours from 2007 in the Inpatient Register and from 2008 in the Causes of Death Register. Our study indicated that several of these tumours were never reported to the Swedish Cancer Register. Thus, the Swedish Cancer Register data cannot be used to dismiss an increased risk for brain tumours associated with use of wireless phones. On the contrary our study is consistent with an association considering a reasonable tumour induction period, see more here: http://www.mdpi.com/1660-4601/12/4/3793

Mechanistic aspects:

It is correct that RF-EMFs do not cause direct DNA damage. On the other hand numerous studies have shown generation of reactive oxygen species (ROS) that can cause oxidative damage of DNA. This is a well-known mechanism in carcinogenesis for many agents. The broad biological potential of ROS and other free radicals makes radiofrequency radiation a potentially hazardous factor for human health, not only cancer risk but also other health effects. A recent update can be read here: http://informahealthcare.com/doi/abs/10.3109/15368378.2015.1043557

Causality:

To further evaluate strengths of evidence Bradford Hill wrote in the 1960’s a famous article on association or causation at the height of the tobacco and lung cancer controversy. Hill offered a list of nine aspects of an association to be considered when deciding if an association is causal. However, he did not request all nine viewpoints to be fulfilled for causality. We used the Hill criteria to evaluate the causality on brain tumor risk from RF-EMF emitted from wireless phones. We concluded that based on the Hill criteria, glioma and acoustic neuroma should be considered to be caused by RF-EMF emissions from wireless phones and regarded as carcinogenic to humans, classifying it as Group 1 according to the IARC classification. Current guidelines for exposure need to be urgently revised. See more here: http://www.degruyter.com/view/j/reveh.2013.28.issue-2-3/reveh-2013-0006/reveh-2013-0006.xml

Conclusion:

Our results are in agreement with other studies such as the international Interphone study and the French so called CERENAT study. This is discussed in e.g. our article on glioma risk. In summary there is consistent evidence of increased risk for glioma and acoustic neuroma associated with use of mobile phones and cordless phones. Furthermore, the risk is highest for persons with first use before the age of 20, which is of special concern. Our conclusion is that RF-EMF should be regarded as a human carcinogen. The IARC classification should be updated to at least Group 2A, a probable human carcinogen. It is necessary to give the public correct information on the cancer risk. The precautionary principle should be used to minimize exposure to RF-EMF. Media have an important role to inform in a balanced way. Unfortunately this article in the New York Times is biased towards the no risk assumption. It should be corrected based on facts and not wishful thinking.

Overall no consistent association was found for use of wireless phones, although somewhat increased risk was found in the group with highest cumulative use of wireless phones and longest latency period (time from first use until diagnosis). These results are similar to findings in other studies in this area. Our results are in contrast to the clearly increased risk for glioma and acoustic neuroma in the same studies. All types of brain tumours were investigated. Thus, different findings for different tumour types clearly show that the results cannot be explained by bias. In that case similar results would have been obtained regardless of tumour type.

Increased risk was found for analogue phone use; OR = 3.75, 95 % CI = 0.97-14.43, and digital mobile phone use only; OR = 2.71, 95 % CI = 1.03-7.10. Risks were higher for temporal tumours, occupational and urban mobile phone use. Unfortunately the study did not include use of cordless phones (DECT) which leads to underestimate of the risks since such use was regarded as no exposure to radiofrequency electromagnetic fields (RF-EMF).

The study included also cases with meningioma. A statistically significant increased risk was found for cumulative duration of calls > 896 hours yielding OR = 2.57, 95 % CI = 1.02-6.44. However, overall the results were less consistent for an association than for gliomas.

No consistent association between use of mobile phones and cordless phones and risk meningioma has been shown in previous studies by our research group in Sweden and the Interphone study at IARC (WHO).

Thus, in the same studies different risks have been found for different tumour types; increased risk for malignant brain tumours (mostly glioma) and acoustic neuroma but not for meningioma. These results clearly indicate that the results cannot be explained by systematic bias in the studies. The conclusion is that wireless phones cause malignant brain tumours and acoustic neuroma.